Published Version

Abstract

Seismic refraction methods are used in environmental and engineering studies to image the
shallow subsurface. We present a blind test of inversion and tomographic refraction analysis
methods using a synthetic first-arrival-time dataset that was made available to the community in
2010. The data are realistic in terms of the near-surface velocity model, shot-receiver geometry
and the data’s frequency and added noise. Fourteen estimated models were determined by ten
participants using eight different inversion algorithms, with the true model unknown to the
participants until it was revealed at a session at the 2011 SAGEEP meeting. The estimated
models are generally consistent in terms of their large-scale features, demonstrating the
robustness of refraction data inversion in general, and the eight inversion algorithms in
particular. When compared to the true model, all of the estimated models contain a smooth
expression of its two main features: a large offset in the bedrock and the top of a steeply dipping
low-velocity fault zone. The estimated models do not contain a subtle low-velocity zone and
other fine-scale features, in accord with conventional wisdom. Together, the results support
confidence in the reliability and robustness of modern refraction inversion and tomographic
Methods.